Lately, in terms of energy saving or global environment issues, reducing burden of air conditioning equipment is required. For example, in the fields of automobiles and house construction, it is required that the temperature in a room or a cabin of a vehicle is controlled by laying an infrared shielding material, which is capable of blocking the infrared rays of sunlight, on window glasses.
Various materials capable of blocking the infrared rays are known. Patent Document 1 discloses a high insulating laminated glass for reflecting rays of light at a specific wavelength in the infrared region. The insulating laminated glass is obtained by laminating, between at least two opposite glass substrates: an infrared reflecting film made of a multilayer film (dielectric multilayer film) where a high refractive index layer and a low refractive index layer are alternately laminated; and a functional laminated interlayer film (fine particle film) in which electroconductive ultrafine particles (such as antimony-doped tin oxide) for blocking the infrared rays are uniformly dispersed. In order to manufacture the high insulating laminated glass, the dielectric multilayer film and the fine particle film are needed to be formed separately, which causes a problem of manufacturing cost.
Patent Document 2 discloses a laminated glass for vehicle windows for reflecting rays of light at a specific wavelength in the infrared region. The laminated glass is obtained by laminating, between a first glass plate and a second glass plate: an laminated film (dielectric multilayer film) where a high refractive index inorganic material layer and a low refractive index inorganic material layer are alternately laminated; and an interlayer film (fine particle film) in which infrared shielding fine particles such as ITO (indium tin oxide) are dispersed and contained. In order to manufacture the laminated glass for vehicle windows, the dielectric multilayer film and the fine particle film are needed to be formed separately, which causes a problem of manufacturing cost.
Patent Document 3 discloses an insulating glass obtained by alternately laminating, on a glass substrate, a transparent conductive layer and a high refractive index layer. The high refractive layer has a relatively high refractive index in the infrared region compared with the refractive index of the transparent conductive layer. However, in the insulating glass, the layer composed of only conductor is used as the low refractive index layer in the infrared region. Thus, it cannot be used in any system of which radio wave transmissibility is required so as to transmit and receive, for example, signals of a mobile phone, a TV and a GPS (global positioning system) inside or outside the room. Furthermore, for the insulating glass, vacuum facilities for sputtering and the like are needed to form the layer composed of only the conductor, which causes a problem of manufacturing cost.